There are many commercially successful non-volatile memory products being used today, particularly in the form of small form factor cards, which employ flash EEPROM (Electrically Erasable and Programmable Read Only Memory) cells formed on one or more integrated circuit devices. Some of the commercially available card formats include Smart Cards, Subscriber Identity Module (SIM), and Removable User Identity Module (R-UIM) cards. These cards typically contain memory and a microcontroller (with associated logic memory and software). The data stored within a card is accessed via an interface that is controlled by a program and, in some cases, security hardware or software.
Typically, SIM cards and R-UIM cards are utilized in cellular telephones operating on Global System for Mobile communication (GSM) and Code Division Multiple Access (CDMA) networks, respectively. In these applications, SIM and R-UIM cards store limited amounts of information, such as encryption keys, subscriber identification values, and telephone contact lists. However, as the storage density of non-volatile memory has increased, more non-volatile memory may be contained within a storage card such as a SIM card. The additional storage may be utilized for a variety of advanced mobile services, such as storing Multimedia Messaging Service (MMS) object attachments, MP3 audio files, high-resolution images files, and video files, as well as providing full personal information management (PIM) functionality, such as e-mail contact lists and calendars. A Mobile Network Operator (MNO) may provide or sell digital content, such as video, picture, and audio files, which may be stored in the additional storage space of a high-capacity card. An example of a high-capacity SIM card is the SIM 5000™, a memory device from SanDisk Corporation of Milpitas, Calif.
The greater storage capacity of a high-capacity SIM card necessitates a faster interface to access the storage contents. The ISO 7816 interface utilized on a typical SIM card, or R-UIM card may be supplemented with an additional high speed interface, such as a Multimedia Card (MMC) interface, a Secure Digital (SD) interface, a Universal Serial Bus (USB), or a Serial Advanced Technology Attachment (SATA) interface, in order to access the storage space of high-capacity cards. The relatively slower ISO 7816 interface may still be utilized for backwards-compatibility purposes, or to control the storage accessible over the high-speed interface. An MNO may utilize the security features of a high-capacity SIM or R-UIM card to prevent copying of the content downloaded by or sold to a cellular telephone subscriber, or to prevent access to the content by unauthorized users or applications.
Some cellular telephones may access a SIM or R-UIM card over an ISO 7816 interface, but may not be capable of utilizing the additional storage space of high-capacity SIM or R-UIM card. Other cellular telephones may support additional storage by providing a receptacle for an additional non-volatile memory card, such as a CompactFlash (CF) card, a MultiMedia Card (MMC), a Secure Digital (SD) card, or a USB Flash Drive. However, an MNO may not be able to prevent copying or unauthorized access to content downloaded or sold to a cellular telephone subscriber that is stored on the additional card, because the additional card may not contain the security features of a high-capacity SIM or R-UIM card.